/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.attribute;

import proguard.classfile.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;

/**
 * This abstract class represents an attribute that is attached to a class, a class member, or a code attribute.
 * Specific types of attributes are subclassed from it.
 *
 * @author Eric Lafortune
 * @noinspection AbstractClassWithoutAbstractMethods
 */
public abstract class Attribute implements VisitorAccepter {
    public int u2attributeNameIndex;
    // public int u4attributeLength;
    // public byte info[];

    /**
     * An extra field in which visitors can store information.
     */
    public Object visitorInfo;

    /**
     * Create an uninitialized Attribute.
     */
    protected Attribute() {}

    /**
     * Create an initialized Attribute.
     */
    protected Attribute(int u2attributeNameIndex) {
        this.u2attributeNameIndex = u2attributeNameIndex;
    }

    /**
     * Returns the String name of the attribute.
     */
    public String getAttributeName(Clazz clazz) {
        return clazz.getString(u2attributeNameIndex);
    }

    // Methods to be implemented by extensions, if applicable.

    /**
     * Accepts the given visitor.
     */
    public void accept(Clazz clazz, AttributeVisitor attributeVisitor) {
        throw new UnsupportedOperationException(
            "Method must be overridden in [" + this.getClass().getName() + "] if ever called");
    }

    /**
     * Accepts the given visitor in the context of the given field.
     */
    public void accept(Clazz clazz, Field field, AttributeVisitor attributeVisitor) {
        // Delegate to the default invocation if the field is null anyway.
        if (field == null) {
            accept(clazz, attributeVisitor);
        } else {
            throw new UnsupportedOperationException(
                "Method must be overridden in [" + this.getClass().getName() + "] if ever called");
        }
    }

    /**
     * Accepts the given visitor in the context of the given method.
     */
    public void accept(Clazz clazz, Method method, AttributeVisitor attributeVisitor) {
        // Delegate to the default invocation if the method is null anyway.
        if (method == null) {
            accept(clazz, (Field)null, attributeVisitor);
        } else {
            throw new UnsupportedOperationException(
                "Method must be overridden in [" + this.getClass().getName() + "] if ever called");
        }
    }

    /**
     * Accepts the given visitor in the context of the given code attribute.
     */
    public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, AttributeVisitor attributeVisitor) {
        // Delegate to the default invocation if the code attribute is null
        // anyway.
        if (codeAttribute == null) {
            accept(clazz, method, attributeVisitor);
        } else {
            throw new UnsupportedOperationException(
                "Method must be overridden in [" + this.getClass().getName() + "] if ever called");
        }
    }

    // Implementations for VisitorAccepter.

    public Object getVisitorInfo() {
        return visitorInfo;
    }

    public void setVisitorInfo(Object visitorInfo) {
        this.visitorInfo = visitorInfo;
    }
}
